Abstract
RS3PE （Remitting Seronegative Symmetrical Synovitis with Pitting Edema） syndrome has been reported as an irAE （immune-related adverse event） of immune checkpoint inhibitor （ICI）. RS3PE syndrome induced by ICI of head and neck cancer has not been reported, and so we report it as an irAE that should be noted. A 62-year-old male patient with pulmonary metastasis that developed after curative chemoradiotherapy for oropharyngeal cancer （p16-positive cT3N1M0 Stage Ⅱ） was second-line treated by pembrolizumab. Edema and pain of both hands and feet were observed after the third cycle of pembrolizumab infusion. Antinuclear antibody, RF, and anti-CCP antibody were negative. RS3PE syndrome was diagnosed definitively. Steroid treatment improved the symptoms, which made it possible to continue pembrolizumab therapy, and the pulmonary metastasis was well controlled.
